1. Field of the Invention
The present invention relates to a display system and a microdisplay apparatus, and more particularly, to a display system and a microdisplay apparatus suitable for data communication via a display interface capable of plug and play.
2. Description of the Related Art
There is an interface conformed with DDC1/DDC2B/DDC2AB standard which is prescribed by VESA (Video Electronics Standards Association) as means for communication between a personal computer and a display apparatus. Further, there is EDID (Extended Display Identification Data Standard) as a data format on which specific information of the display apparatus is recognized by the personal computer by using the communication via the above interface.
In an example of the above-mentioned communication, as disclosed in Japanese Unexamined Patent Application Publication No. 10-74072, there is provided a display apparatus, connected to a computer main body, for displaying data of a computer main body on a monitor, having a monitor control unit for display control with a CPU and a RAM and a nonvolatile memory connected to the monitor control unit, wherein the nonvolatile memory has an area for storing monitor specification data necessary for set-up of display and the RAM has an area for downloading the monitor specification data when the computer main body is turned on or is reset, and the monitor specification data downloaded is transferred to the computer main body in accordance with a reading request from the computer main body.
Recently, portable-type personal computers are increasingly developed and many companies unveil small personal computers which operate with a battery and integrate no display apparatus. The small personal computers are well known as, a so-called wearable computers. As one of the display apparatuses in the wearable computers, there is a portable-type microdisplay apparatus or wearable display apparatus developed having a small display (display having a diagonal length of a screen of, for example, 50 mm or less). An unveiled concrete case is a monocular-type head mounted video display apparatus using a digital video interface. In the wearable computer system, the microdisplay apparatus is mounted on the head or face, a wearable computer is equipped, and the microdisplay apparatus and wearable computer are connected, thereby using the system.
The display interface of some of these microdisplay apparatus adopts a signal format of GVIF, TMDS, or LVDS. The microdisplay apparatus using the signal formats is specified to greatly reduce power consumption, as compared with general display apparatuses. Specifically speaking, the power consumption is, for example, approximately 5V and 0.5 A. Therefore, even when a host apparatus is portable-type information equipment driven with the battery as mentioned above (e.g., a notebook-type personal computer and a wearable personal computer), power can be supplied from the host apparatus.
Currently, companies sell portable-type DVD players. In addition, as unveiled ones, there is a portable-type DVD player in which a dedicated output terminal for supplying a video signal and power via a dedicated connection cable is provided for a commercial head mounted video display apparatus.
By using the video interface of the DVD player, a plurality of kinds of display apparatuses can be exchanged and employed.
In recent years, because of difficult setting in that peripheral equipment is connected to a computer as the host apparatus, a plug and play mechanism is integrated in the computer system or the like to facilitate the setting. In the plug and play mechanism, only by plugging the peripheral equipment in, for instance, a personal computer, the computer can readily play.
The plug and play is structured by a BIOS corresponding to the plug and play and an OS (operating system) corresponding to it. For example, the plug and play mechanism enables the automation of troublesome setting of the system such as setting of interrupt of expansion board (IRQ), DMA channel, I/O address, etc. and also enables a device driver of a peripheral equipment to be automatically loaded/unloaded when the peripheral equipment are attached to or detached from the personal computer during operation thereof.
The display apparatus having the above-described plug and play mechanism (function) is produced. Data of the display apparatus such as a resolution and a synchronous frequency is received/transmitted between the computer and the plug and play mechanism of the display apparatus, thereby effecting the plug and play mechanism.
In the above-described plug and play mechanism of the display, control for communication is performed through a DDC (Display Data Channel) interface which is standardized by the VESA. Also, by transmitting EDID (Extended Display Identification Data) information on the resolution and the synchronous frequency of the display apparatus, etc. from the display apparatus to the computer, the setting can be automatized to recognize an available range of the display apparatus. On the other hand, the plug and play needs complicated operations of start, selection, and execution of application.
The improvement in the operability is, for instance, a display apparatus disclosed in Japanese Unexamined Patent Application Publication No. 11-15425. The display apparatus has a function for switching a display mode of a computer under the control of an operation for switching a resolution and a synchronous frequency by the display apparatus itself so as to improve the operability. The disclosure exemplifies a case in which the computer is connected to the display apparatus with one-to-one corresponding relationship, that is, the single display apparatus is connected to the computer.
As general display apparatuses, there are a CRT display used for a desk-top computer and a liquid crystal display used for the liquid crystal desk-top computer. However, power consumption is large in these displays. Therefore, general types are a display integrating an AC power supply and a display to which DC power is supplied via an AC adapter. In the plug and play of the above-mentioned display apparatus, the improvement is limited to the automatization of setting of the resolution and synchronous frequency of the display apparatus. A digital interface of the display apparatus is disclosed in Japanese Patent Unexamined Publication No. 9-311670 as one example. In the interface disclosed therein, however, there is neither suggestion nor consideration of power control.
Since the above application is typical, it is necessary to supply a power supply of the display apparatus from the AC power or from the AC adapter near the installed place of the display apparatus when using the display apparatus at a position far from the host apparatus.
Also, since the above-mentioned wearable computer system is developed in terms of connection of a dedicated display apparatus, it is not assumed that microdisplay apparatuses having various specifications are exchanged and connected. Thus, the plug and play is not considered.
In recent years, in association with the active technical development in the field of the microdisplay apparatus, a technique for connecting pieces of equipment for general purpose must be taken into account.
However, it is difficult to implement the plug and play connection via a shared interface between the host apparatus and the display apparatus to which a video signal and power are supplied from the host apparatus because of the following reasons.
Firstly, in the standard specification of the above EDID, there is no item on power consumption of the display apparatus to be connected and data on the power consumption is not supported. Consequently, in the case of supplying power to the display apparatus from the host apparatus, even if no power consumption of the display apparatus connected to the host apparatus corresponds to the power capacity of the host apparatus, there is a possibility that the host apparatus feeds power.
Next, according to the aforementioned technique, power can be controlled by storing a power consumption data file of the existing display apparatus in the host apparatus, then, by recognizing the display apparatus connected to the host apparatus in accordance with the EDID, and by referring to the corresponding data file. However, even in this case, it is not possible to control the power for the display apparatus in which, beforehand, the data file is not provided in the host apparatus.
Further, in a display system in which a HOST APPARATUS is driven with a battery and a video signal and power are supplied to a display apparatus from the HOST APPARATUS, the HOST APPARATUS has no power consumption data of the display apparatus connected thereto. Therefore, it is impossible to correctly recognize available time of the host apparatus and the display apparatus corresponding to a residual amount of battery power in the host apparatus and, then, the available time cannot also be correctly indicated to a user.
In some face mounted display (FMD) system as a product, a controller for manual operation lies between a host apparatus as a supply source of a video image and a goggle as a display apparatus mounted on the head upon using. However, for the purpose of conveniently carrying the FMD system, the high portability is desired for applications such as the wearable personal computer PC (Personal Computer) and, thus, the configuration needs to be simplified as much as possible.
It is considered that, in place of independent installation of the controller, the host apparatus or goggle has a function of the controller and only the goggle is directly connected to the host apparatus.
However, the controller has an on-screen display (OSD) function for displaying information on a product (such as the residual amount of battery power and a screen of a password) on a screen for the user who mounts the goggle on the head. In one example of the OSD function, if the goggle entirely has this function, the goggle increases in size and the user cannot comfortably mount it on the head.
As another example of the OSD function, there is a password function for setting the goggle to be connected to a personal computer. Originally, the goggle has a password as unique information. In the case in which the password function is provided for the host apparatus, a specific goggle is connected to a specific host apparatus with one-to-one corresponding relationship and the availability is limited, thus prohibiting the general-purpose use. In conclusion, it is not preferable to provide the password function for the host apparatus.
As described above, further, the existing display systems such as the FMD system need improvement of the portability and have a problem in that the goggle is increased in size and cannot be wearablly used if the controller is not provided to accomplish the above necessary improvement without any devices.
As one of the display systems, a power-down converter and power-up converter are provided for the microdisplay apparatus and a power supply of the power-up/down converters is controlled by the microdisplay apparatus itself and the operation thereof is made stable. In this case, most often, power consumption of the power-up/down converter is large and the weight thereof is heavy.
Preferably, the display apparatus is formed by enclosing the power supply in one cable so that the portability is high and it is easily used for an operator. Although the digitization of a video signal enables long-distance communication, it must be taken into account that a voltage of a power supply drops in accordance with a length of a cable when a line for transmitting the video signal and a line for supplying power is shared. Consequently, if the host apparatus is detached/attached from/to the operator in consideration of the above points, it is desired that the microdisplay apparatus can be operated wearablly and stably.
No apparatus for displaying data on a screen by connecting a plurality of equipment is disclosed in the Japanese Unexamined Patent Application Publication No. 11-15425. More specifically, if the computer is connected to the display apparatus via a conversion adapter, etc. arranged between them, the plug and play may become ineffective. Such problem is not taken into account therein. In the plug and play, only a point is considered that the microdisplay apparatus is directly communicated with the computer, thereby receiving and transmitting data. Therefore, the above plug and play is not effective to a system for converting a format of the video signal by the conversion adapter and displaying the signal on the microdisplay apparatus.